This dataset contains half-hourly averaged volatile organic compound concentrations and fluxes obtained above a maize field at the Lonzée ICOS ecosystem site in Belgium, from May to October 2012. The concentration data were obtained with a hs-PTR-Quad-MS instrument (Ionicon Analytik GmbH, Austria) and micrometeorological flux data were obtained with the disjunct eddy covariance by mass scanning method. Methodological aspects and data analysis have been described in "Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season" by Bachy et al., https://doi.org/10.5194/acp-16-5343-2016, 2016. Part of the dataset was also used in Bachy et al., https://doi.org/10.1016/j.atmosenv.2017.12.016, 2018. The dataset is provided as a csv file (size 4.921 KB) and a complete list of all variables is given in the accompanying "Dataset_Lonzée_2012_variables" text file. All ancillary data measured at the site are publicly available and can be obtained ...